作者:Mara L. Zanini、Mario R. Meneghetti、Gunter Ebeling、Paolo R. Livotto、Frank Rominger、Jairton Dupont
DOI:10.1016/s0277-5387(03)00324-3
日期:2003.7
The bridge-splitting reaction of dimeric palladacycles of the type Pd[kappa(1)-C, kappa(1)-N-C(R) = C(Cl)CH2NMe2](mu-Cl)}(2) (R = Ph, Me, CH2CH2OH), derived from the chloropalladation of propargyl amines (RCdropCCH(2)NMe(2)), with pyridine (Py), triphenylphosphine (PPh3) and tert-butytisonitrile ((BuNC)-Bu-t) affords the monomeric compounds [PdC(R)=CCH2NMe2(Cl)L] (L = Py, PPh3, (BuNC)-Bu-t). These monomeric compounds are not stable in solution and undergo retro-chloropalladation reactions yielding the propargyl amines and [PdCl(L)-mu-Cl](2). This process is strongly dependent upon the nature of the incoming nucleophile (L), the R group on the metallated ligand and the temperature. The retro-halopalladation reaction is almost instantaneous in the case of the reaction of the bromo derivative [PdC(Ph)=C(Br)CH2NMe2-mu-Br](2) and pyridine at room temperature. These results can be rationalized in terms of the stability of the Pd-C bond of the intermediate monomeric compound [PdC(R)=C(X)CH2NMe2(X)L], that is directly related to the nature of its substituents R (Ph, Me and CH2CH2OH), of ligands which are both cis and trans to it (Py, (CNBu)-Bu-t, PPh3, Cl and Br) and the temperature. (C) 2003 Elsevier Science Ltd. All rights reserved.